We have had some problems with the E Class (210) headlight assemblies leaking water in them and always replace the whole assemblies. There was also a modification on the front parking lights, because they were melting the bulb holders causing they bulb light indicator to come on all the time. If they changed out 1 of your headlight assemblies, then make sure the other headlight has been modified. They will fix it under warranty. This affected 1996 through early 1998 E Class cars (210). As for the seat heater, there are 2 heating grids in the seats, seat back and seat bottom. The grids are built into the leather bottoms. Thats why you only got that portion replaced. Hope this helps you out!
Factory Trained Mercedes-Benz technician